How to read ripples in DC without Oscilliscope, or any other analyzer!

Discussion in 'Homework Help' started by hamza, Dec 26, 2007.

  1. hamza

    Thread Starter New Member

    Feb 8, 2007
    I've been looking everywhere for the answer, but I really can't find it.

    What is the method of measuring, or checking or even just analyzing the "ripples" in DC without the use of any analyzer device like the oscilloscope?
  2. thingmaker3

    Retired Moderator

    May 16, 2005
    If you know component values, you can calculate an estimate of ripple based on them.
  3. hamza

    Thread Starter New Member

    Feb 8, 2007
    oh thanks for replying! this is actually an assignment which I have to submit by tomorrow. There are no provied component values or any other things like that. Just a single question. I can't find out because previously I was just into finding this out with the oscilloscope!

    Can you tell me what values should be known, and any relation (formula) which can be used to measure the ripple?
  4. JoeJester

    AAC Fanatic!

    Apr 26, 2005
    You place your oscilloscope in the AC mode. Trigger the oscilloscope with line or whatever the generates the basic frequency before the diodes.

    The ripple will be synchronous with the trigger signal.
  5. mrmeval

    Distinguished Member

    Jun 30, 2006
    Place your meter in AC mode and you can read the AC component.
  6. SgtWookie


    Jul 17, 2007
    Not all meters (particularly old ones) will block the DC component.

    If you use a low-leakage capacitor on one of the test probes, it will block the DC component, but pass the effects of the AC component. If the ripple is a pure sine wave, then the AC scale of a true RMS meter will give you the RMS (average) voltage, and the peak-peak voltage will be the RMS reading multiplied by 1.414 (not exact, but close.) If the ripple is other than a pure sine wave, the RMS reading will be off depending on how distorted the sine wave is.
  7. techroomt

    Senior Member

    May 19, 2004
    a multimeter will measure the ac component of a signal as mrmeval explained, with a few exceptions:

    1. an ac meter (multimeter) will "read" the rms value (not average)
    2. the meter is designed to read 60 hz, so anything else will provide error. you can go to "freq" if the meter has that function and read the frequency
    3. anything other then pure sine wave will also provide error
  8. hamza

    Thread Starter New Member

    Feb 8, 2007
    oh ya! this solves my problem! thank u all!! :)